Glycolysis in a cell extract

Hey minjai0322, the limiting reactant in glycolysis is always glucose, but in this case it is NAD+ because you need 2 NAD+ molecules for every glucose molecule that is converted and you only have 20 from the beginning. So, glycolysis will stop after 10 glucose molecules (therefore 10 glucose molecules leftover - poor glucose).

(b) So we know that in 1 round of glycolysis, you need:

1 glucose
You lose 2 ATPs but you make 4 ATPs = 2 left over (So... +2 ATP)
-4 ADP
+2 NADH
-2 NAD+

So, at the end:

-10 glucose molecules (negative 20)
-20 ATP molecules
-20 ADP
+40 ATP molecules (but minus the 20 used, you are left with 20 ATP gained... plus the 30 left over = 50 TOTAL ATP altogether)
+20 NADH
-20 NAD+
Since you created 40 ATP... you used 40 moles of phosphate. However, you gain phosphate from the dephosphorylation of ATP to ADP. In 10 glucose molecules converted, we gained 20 phosphates, so we are left with 20 phosphate molecules.

Not sure about (c); can you provide a bit more detail?

Here is a good diagram to keep track of all the molecules.

Could you answer (c) of this problem?

I think it's kind of already stated minjai0322. Just work through what you started with and what you end with.

When know that for each cycle of glycolysis, you lose 1 glucose, lose 2 ATP, gain two ADP, loss two phosphates, gain 4 ATPS, loss four phosphates, gain 2 NADH, loss two NAD+... Do that 10 more times and see how much you are left with.